// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/ext4/page-io.c
*
* This contains the new page_io functions for ext4
*
* Written by Theodore Ts'o, 2010.
*/
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/highuid.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include <linux/pagevec.h>
#include <linux/mpage.h>
#include <linux/namei.h>
#include <linux/uio.h>
#include <linux/bio.h>
#include <linux/workqueue.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
#include "ext4_jbd2.h"
#include "xattr.h"
#include "acl.h"
static struct kmem_cache *io_end_cachep;
static struct kmem_cache *io_end_vec_cachep;
int __init ext4_init_pageio(void)
{
io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
if (io_end_cachep == NULL)
return -ENOMEM;
io_end_vec_cachep = KMEM_CACHE(ext4_io_end_vec, 0);
if (io_end_vec_cachep == NULL) {
kmem_cache_destroy(io_end_cachep);
return -ENOMEM;
}
return 0;
}
void ext4_exit_pageio(void)
{
kmem_cache_destroy(io_end_cachep);
kmem_cache_destroy(io_end_vec_cachep);
}
struct ext4_io_end_vec *ext4_alloc_io_end_vec(ext4_io_end_t *io_end)
{
struct ext4_io_end_vec *io_end_vec;
io_end_vec = kmem_cache_zalloc(io_end_vec_cachep, GFP_NOFS);
if (!io_end_vec)
return ERR_PTR(-ENOMEM);
INIT_LIST_HEAD(&io_end_vec->list);
list_add_tail(&io_end_vec->list, &io_end->list_vec);
return io_end_vec;
}
static void ext4_free_io_end_vec(ext4_io_end_t *io_end)
{
struct ext4_io_end_vec *io_end_vec, *tmp;
if (list_empty(&io_end->list_vec))
return;
list_for_each_entry_safe(io_end_vec, tmp, &io_end->list_vec, list) {
list_del(&io_end_vec->list);
kmem_cache_free(io_end_vec_cachep, io_end_vec);
}
}
struct ext4_io_end_vec *ext4_last_io_end_vec(ext4_io_end_t *io_end)
{
BUG_ON(list_empty(&io_end->list_vec));
return list_last_entry(&io_end->list_vec, struct ext4_io_end_vec, list);
}
/*
* Print an buffer I/O error compatible with the fs/buffer.c. This
* provides compatibility with dmesg scrapers that look for a specific
* buffer I/O error message. We really need a unified error reporting
* structure to userspace ala Digital Unix's uerf system, but it's
* probably not going to happen in my lifetime, due to LKML politics...
*/
static void buffer_io_error(struct buffer_head *bh)
{
printk_ratelimited(KERN_ERR "Buffer I/O error on device %pg, logical block %llu\n",
bh->b_bdev,
(unsigned long long)bh->b_blocknr);
}
static void ext4_finish_bio(struct bio *bio)
{
struct folio_iter fi;
bio_for_each_folio_all(fi, bio) {
struct folio *folio = fi.folio;
struct folio *io_folio = NULL;
struct buffer_head *bh, *head;
size_t bio_start = fi.offset;
size_t bio_end = bio_start + fi.length;
unsigned under_io = 0;
unsigned long flags;
if (fscrypt_is_bounce_folio(folio)) {
io_folio = folio;
folio = fscrypt_pagecache_folio(folio);
}
if (bio->bi_status) {
int err = blk_status_to_errno(bio->bi_status);
mapping_set_error(folio->mapping, err);
}
bh = head = folio_buffers(folio);
/*
* We check all buffers in the folio under b_uptodate_lock
* to avoid races with other end io clearing async_write flags
*/
spin_lock_irqsave(&head->b_uptodate_lock, flags);
do {
if (bh_offset(bh) < bio_start ||
bh_offset(bh) + bh->b_size > bio_end) {
if (buffer_async_write(bh))
under_io++;
continue;
}
clear_buffer_async_write(bh);
if (bio->bi_status) {
set_buffer_write_io_error(bh);
buffer_io_error(bh);
}
} while ((bh = bh->b_this_page) != head);
spin_unlock_irqrestore(&head->b_uptodate_lock, flags);
if (!under_io) {
fscrypt_free_bounce_page(&io_folio->page);
folio_end_writeback(folio);
}
}
}
static void ext4_release_io_end(ext4_io_end_t *io_end)
{
struct bio *bio, *next_bio;
BUG_ON(!list_empty(&io_end->list));
BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
WARN_ON(io_end->handle);
for (bio = io_end->bio; bio; bio = next_bio) {
next_bio = bio->bi_private;
ext4_finish_bio(bio);
bio_put(bio);
}
ext4_free_io_end_vec(io_end);
kmem_cache_free(io_end_cachep, io_end);
}
/*
* Check a range of space and convert unwritten extents to written. Note that
* we are protected from truncate touching same part of extent tree by the
* fact that truncate code waits for all DIO to finish (thus exclusion from
* direct IO is achieved) and also waits for PageWriteback bits. Thus we
* cannot get to ext4_ext_truncate() before all IOs overlapping that range are
* completed (happens from ext4_free_ioend()).
*/
static int ext4_end_io_end(ext4_io_end_t *io_end)
{
struct inode *inode = io_end->inode;
handle_t *handle = io_end->handle;
int ret = 0;
ext4_debug("ext4_end_io_nolock: io_end 0x%p from inode %lu,list->next 0x%p,"
"list->prev 0x%p\n",
io_end, inode->i_ino, io_end->list.next, io_end->list.prev);
io_end->handle = NULL; /* Following call will use up the handle */
ret = ext4_convert_unwritten_io_end_vec(handle, io_end);
if (ret < 0 && !ext4_forced_shutdown(inode->i_sb)) {
ext4_msg(inode->i_sb, KERN_EMERG,
"failed to convert unwritten extents to written "
"extents -- potential data loss! "
"(inode %lu, error %d)", inode->i_ino, ret);
}
ext4_clear_io_unwritten_flag(io_end);
ext4_release_io_end(io_end);
return ret;
}
static void dump_completed_IO(struct inode *inode, struct list_head *head)
{
#ifdef EXT4FS_DEBUG
struct list_head *cur, *before, *after;
ext4_io_end_t *io_end, *io_end0, *io_end1;
if (list_empty(head))
return;
ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
list_for_each_entry(io_end, head, list) {
cur = &io_end->list;
before = cur->prev;
io_end0 = container_of(before, ext4_io_end_t, list);
after = cur->next;
io_end1 = container_of(after, ext4_io_end_t, list);
ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
io_end, inode->i_ino, io_end0, io_end1);
}
#endif
}
/* Add the io_end to per-inode completed end_io list. */
static void ext4_add_complete_io(ext4_io_end_t *io_end)
{
struct ext4_inode_info *ei = EXT4_I(io_end->inode);
struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb);
struct workqueue_struct *wq;
unsigned long flags;
/* Only reserved conversions from writeback should enter here */
WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
WARN_ON(!io_end->handle && sbi->s_journal);
spin_lock_irqsave(&ei->i_completed_io_lock, flags);
wq = sbi->rsv_conversion_wq;
if (list_empty(&ei->i_rsv_conversion_list))
queue_work(wq, &ei->i_rsv_conversion_work);
list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
}
static int ext4_do_flush_completed_IO(struct inode *inode,
struct list_head *head)
{
ext4_io_end_t *io_end;
struct list_head unwritten;
unsigned long flags;
struct ext4_inode_info *ei = EXT4_I(inode);
int err, ret = 0;
spin_lock_irqsave(&ei->i_completed_io_lock, flags);
dump_completed_IO(inode, head);
list_replace_init(head, &unwritten);
spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
while (!list_empty(&unwritten)) {
io_end = list_entry(unwritten.next, ext4_io_end_t, list);
BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
list_del_init(&io_end->list);
err = ext4_end_io_end(io_end);
if (unlikely(!ret && err))
ret = err;
}
return ret;
}
/*
* work on completed IO, to convert unwritten extents to extents
*/
void ext4_end_io_rsv_work(struct work_struct *work)
{
struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
i_rsv_conversion_work);
ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
}
ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
{
ext4_io_end_t *io_end = kmem_cache_zalloc(io_end_cachep, flags);
if (io_end) {
io_end->inode = inode;
INIT_LIST_HEAD(&io_end->list);
INIT_LIST_HEAD(&io_end->list_vec);
refcount_set(&io_end->count, 1);
}
return io_end;
}
void ext4_put_io_end_defer(ext4_io_end_t *io_end)
{
if (refcount_dec_and_test(&io_end->count)) {
if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) ||
list_empty(&io_end->list_vec)) {
ext4_release_io_end(io_end);
return;
}
ext4_add_complete_io(io_end);
}
}
int ext4_put_io_end(ext4_io_end_t *io_end)
{
int err = 0;
if (refcount_dec_and_test(&io_end->count)) {
if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
err = ext4_convert_unwritten_io_end_vec(io_end->handle,
io_end);
io_end->handle = NULL;
ext4_clear_io_unwritten_flag(io_end);
}
ext4_release_io_end(io_end);
}
return err;
}
ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
{
refcount_inc(&io_end->count);
return io_end;
}
/* BIO completion function for page writeback */
static void ext4_end_bio(struct bio *bio)
{
ext4_io_end_t *io_end = bio->bi_private;
sector_t bi_sector = bio->bi_iter.bi_sector;
if (WARN_ONCE(!io_end, "io_end is NULL: %pg: sector %Lu len %u err %d\n",
bio->bi_bdev,
(long long) bio->bi_iter.bi_sector,
(unsigned) bio_sectors(bio),
bio->bi_status)) {
ext4_finish_bio(bio);
bio_put(bio);
return;
}
bio->bi_end_io = NULL;
if (bio->bi_status) {
struct inode *inode = io_end->inode;
ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu "
"starting block %llu)",
bio->bi_status, inode->i_ino,
(unsigned long long)
bi_sector >> (inode->i_blkbits - 9));
mapping_set_error(inode->i_mapping,
blk_status_to_errno(bio->bi_status));
}
if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
/*
* Link bio into list hanging from io_end. We have to do it
* atomically as bio completions can be racing against each
* other.
*/
bio->bi_private = xchg(&io_end->bio, bio);
ext4_put_io_end_defer(io_end);
} else {
/*
* Drop io_end reference early. Inode can get freed once
* we finish the bio.
*/
ext4_put_io_end_defer(io_end);
ext4_finish_bio(bio);
bio_put(bio);
}
}
void ext4_io_submit(struct ext4_io_submit *io)
{
struct bio *bio = io->io_bio;
if (bio) {
if (io->io_wbc->sync_mode == WB_SYNC_ALL)
io->io_bio->bi_opf |= REQ_SYNC;
submit_bio(io->io_bio);
}
io->io_bio = NULL;
}
void ext4_io_submit_init(struct ext4_io_submit *io,
struct writeback_control *wbc)
{
io->io_wbc = wbc;
io->io_bio = NULL;
io->io_end = NULL;
}
static void io_submit_init_bio(struct ext4_io_submit *io,
struct buffer_head *bh)
{
struct bio *bio;
/*
* bio_alloc will _always_ be able to allocate a bio if
* __GFP_DIRECT_RECLAIM is set, see comments for bio_alloc_bioset().
*/
bio = bio_alloc(bh->b_bdev, BIO_MAX_VECS, REQ_OP_WRITE, GFP_NOIO);
fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO);
bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
bio->bi_end_io = ext4_end_bio;
bio->bi_private = ext4_get_io_end(io->io_end);
io->io_bio = bio;
io->io_next_block = bh->b_blocknr;
wbc_init_bio(io->io_wbc, bio);
}
static void io_submit_add_bh(struct ext4_io_submit *io,
struct inode *inode,
struct folio *folio,
struct folio *io_folio,
struct buffer_head *bh)
{
if (io->io_bio && (bh->b_blocknr != io->io_next_block ||
!fscrypt_mergeable_bio_bh(io->io_bio, bh))) {
submit_and_retry:
ext4_io_submit(io);
}
if (io->io_bio == NULL)
io_submit_init_bio(io, bh);
if (!bio_add_folio(io->io_bio, io_folio, bh->b_size, bh_offset(bh)))
goto submit_and_retry;
wbc_account_cgroup_owner(io->io_wbc, &folio->page, bh->b_size);
io->io_next_block++;
}
int ext4_bio_write_folio(struct ext4_io_submit *io, struct folio *folio,
size_t len)
{
struct folio *io_folio = folio;
struct inode *inode = folio->mapping->host;
unsigned block_start;
struct buffer_head *bh, *head;
int ret = 0;
int nr_to_submit = 0;
struct writeback_control *wbc = io->io_wbc;
bool keep_towrite = false;
BUG_ON(!folio_test_locked(folio));
BUG_ON(folio_test_writeback(folio));
/*
* Comments copied from block_write_full_folio:
*
* The folio straddles i_size. It must be zeroed out on each and every
* writepage invocation because it may be mmapped. "A file is mapped
* in multiples of the page size. For a file that is not a multiple of
* the page size, the remaining memory is zeroed when mapped, and
* writes to that region are not written out to the file."
*/
if (len < folio_size(folio))
folio_zero_segment(folio, len, folio_size(folio));
/*
* In the first loop we prepare and mark buffers to submit. We have to
* mark all buffers in the folio before submitting so that
* folio_end_writeback() cannot be called from ext4_end_bio() when IO
* on the first buffer finishes and we are still working on submitting
* the second buffer.
*/
bh = head = folio_buffers(folio);
do {
block_start = bh_offset(bh);
if (block_start >= len) {
clear_buffer_dirty(bh);
set_buffer_uptodate(bh);
continue;
}
if (!buffer_dirty(bh) || buffer_delay(bh) ||
!buffer_mapped(bh) || buffer_unwritten(bh)) {
/* A hole? We can safely clear the dirty bit */
if (!buffer_mapped(bh))
clear_buffer_dirty(bh);
/*
* Keeping dirty some buffer we cannot write? Make sure
* to redirty the folio and keep TOWRITE tag so that
* racing WB_SYNC_ALL writeback does not skip the folio.
* This happens e.g. when doing writeout for
* transaction commit or when journalled data is not
* yet committed.
*/
if (buffer_dirty(bh) ||
(buffer_jbd(bh) && buffer_jbddirty(bh))) {
if (!folio_test_dirty(folio))
folio_redirty_for_writepage(wbc, folio);
keep_towrite = true;
}
continue;
}
if (buffer_new(bh))
clear_buffer_new(bh);
set_buffer_async_write(bh);
clear_buffer_dirty(bh);
nr_to_submit++;
} while ((bh = bh->b_this_page) != head);
/* Nothing to submit? Just unlock the folio... */
if (!nr_to_submit)
return 0;
bh = head = folio_buffers(folio);
/*
* If any blocks are being written to an encrypted file, encrypt them
* into a bounce page. For simplicity, just encrypt until the last
* block which might be needed. This may cause some unneeded blocks
* (e.g. holes) to be unnecessarily encrypted, but this is rare and
* can't happen in the common case of blocksize == PAGE_SIZE.
*/
if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
gfp_t gfp_flags = GFP_NOFS;
unsigned int enc_bytes = round_up(len, i_blocksize(inode));
struct page *bounce_page;
/*
* Since bounce page allocation uses a mempool, we can only use
* a waiting mask (i.e. request guaranteed allocation) on the
* first page of the bio. Otherwise it can deadlock.
*/
if (io->io_bio)
gfp_flags = GFP_NOWAIT | __GFP_NOWARN;
retry_encrypt:
bounce_page = fscrypt_encrypt_pagecache_blocks(&folio->page,
enc_bytes, 0, gfp_flags);
if (IS_ERR(bounce_page)) {
ret = PTR_ERR(bounce_page);
if (ret == -ENOMEM &&
(io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) {
gfp_t new_gfp_flags = GFP_NOFS;
if (io->io_bio)
ext4_io_submit(io);
else
new_gfp_flags |= __GFP_NOFAIL;
memalloc_retry_wait(gfp_flags);
gfp_flags = new_gfp_flags;
goto retry_encrypt;
}
printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
folio_redirty_for_writepage(wbc, folio);
do {
if (buffer_async_write(bh)) {
clear_buffer_async_write(bh);
set_buffer_dirty(bh);
}
bh = bh->b_this_page;
} while (bh != head);
return ret;
}
io_folio = page_folio(bounce_page);
}
__folio_start_writeback(folio, keep_towrite);
/* Now submit buffers to write */
do {
if (!buffer_async_write(bh))
continue;
io_submit_add_bh(io, inode, folio, io_folio, bh);
} while ((bh = bh->b_this_page) != head);
return 0;
}
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